Annotation of src/usr.bin/su/su.c, Revision 1.30
1.30 ! deraadt 1: /* $OpenBSD: su.c,v 1.29 1997/06/29 11:10:35 provos Exp $ */
1.4 deraadt 2:
1.1 deraadt 3: /*
4: * Copyright (c) 1988 The Regents of the University of California.
5: * All rights reserved.
6: *
7: * Redistribution and use in source and binary forms, with or without
8: * modification, are permitted provided that the following conditions
9: * are met:
10: * 1. Redistributions of source code must retain the above copyright
11: * notice, this list of conditions and the following disclaimer.
12: * 2. Redistributions in binary form must reproduce the above copyright
13: * notice, this list of conditions and the following disclaimer in the
14: * documentation and/or other materials provided with the distribution.
15: * 3. All advertising materials mentioning features or use of this software
16: * must display the following acknowledgement:
17: * This product includes software developed by the University of
18: * California, Berkeley and its contributors.
19: * 4. Neither the name of the University nor the names of its contributors
20: * may be used to endorse or promote products derived from this software
21: * without specific prior written permission.
22: *
23: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33: * SUCH DAMAGE.
34: */
35:
36: #ifndef lint
37: char copyright[] =
38: "@(#) Copyright (c) 1988 The Regents of the University of California.\n\
39: All rights reserved.\n";
40: #endif /* not lint */
41:
42: #ifndef lint
43: /*static char sccsid[] = "from: @(#)su.c 5.26 (Berkeley) 7/6/91";*/
1.30 ! deraadt 44: static char rcsid[] = "$OpenBSD: su.c,v 1.29 1997/06/29 11:10:35 provos Exp $";
1.1 deraadt 45: #endif /* not lint */
46:
47: #include <sys/param.h>
48: #include <sys/time.h>
49: #include <sys/resource.h>
1.8 millert 50:
51: #include <err.h>
52: #include <errno.h>
53: #include <grp.h>
54: #include <paths.h>
55: #include <pwd.h>
1.1 deraadt 56: #include <stdio.h>
57: #include <stdlib.h>
58: #include <string.h>
1.8 millert 59: #include <syslog.h>
1.1 deraadt 60: #include <unistd.h>
1.8 millert 61:
62: #ifdef SKEY
63: #include <skey.h>
64: #endif
1.1 deraadt 65:
66: #ifdef KERBEROS
1.29 provos 67: #include <des.h>
1.1 deraadt 68: #include <kerberosIV/krb.h>
69: #include <netdb.h>
70:
1.30 ! deraadt 71: int kerberos __P((char *username, char *user, int uid));
! 72:
1.1 deraadt 73: #define ARGSTR "-Kflm"
74:
75: int use_kerberos = 1;
1.28 deraadt 76: char krbtkfile[MAXPATHLEN];
77: char lrealm[REALM_SZ];
78: int ksettkfile(char *);
1.1 deraadt 79: #else
80: #define ARGSTR "-flm"
81: #endif
82:
1.8 millert 83: char *ontty __P((void));
84: int chshell __P((char *));
1.1 deraadt 85:
86: int
87: main(argc, argv)
88: int argc;
89: char **argv;
90: {
91: extern char **environ;
92: register struct passwd *pwd;
93: register char *p, **g;
94: struct group *gr;
1.9 millert 95: uid_t ruid;
1.1 deraadt 96: int asme, ch, asthem, fastlogin, prio;
97: enum { UNSET, YES, NO } iscsh = UNSET;
1.24 deraadt 98: char *user, *shell, *avshell, *username, **np;
1.1 deraadt 99: char shellbuf[MAXPATHLEN], avshellbuf[MAXPATHLEN];
100:
101: asme = asthem = fastlogin = 0;
1.18 millert 102: while ((ch = getopt(argc, argv, ARGSTR)) != -1)
1.1 deraadt 103: switch((char)ch) {
104: #ifdef KERBEROS
105: case 'K':
106: use_kerberos = 0;
107: break;
108: #endif
109: case 'f':
110: fastlogin = 1;
111: break;
112: case '-':
113: case 'l':
114: asme = 0;
115: asthem = 1;
116: break;
117: case 'm':
118: asme = 1;
119: asthem = 0;
120: break;
121: case '?':
122: default:
1.7 millert 123: (void)fprintf(stderr,
124: "usage: su [%s] [login [shell arguments]]\n",
1.1 deraadt 125: ARGSTR);
126: exit(1);
127: }
128: argv += optind;
129:
130: errno = 0;
131: prio = getpriority(PRIO_PROCESS, 0);
132: if (errno)
133: prio = 0;
134: (void)setpriority(PRIO_PROCESS, 0, -2);
135: openlog("su", LOG_CONS, 0);
136:
137: /* get current login name and shell */
138: ruid = getuid();
139: username = getlogin();
140: if (username == NULL || (pwd = getpwnam(username)) == NULL ||
141: pwd->pw_uid != ruid)
142: pwd = getpwuid(ruid);
1.8 millert 143: if (pwd == NULL)
144: errx(1, "who are you?");
1.9 millert 145: if ((username = strdup(pwd->pw_name)) == NULL)
146: err(1, "can't allocate memory");
1.1 deraadt 147: if (asme)
1.10 millert 148: if (pwd->pw_shell && *pwd->pw_shell) {
1.11 millert 149: shell = strncpy(shellbuf, pwd->pw_shell, sizeof(shellbuf) - 1);
1.10 millert 150: shellbuf[sizeof(shellbuf) - 1] = '\0';
151: } else {
1.1 deraadt 152: shell = _PATH_BSHELL;
153: iscsh = NO;
154: }
155:
156: /* get target login information, default to root */
157: user = *argv ? *argv : "root";
158: np = *argv ? argv : argv-1;
159:
1.8 millert 160: if ((pwd = getpwnam(user)) == NULL)
161: errx(1, "unknown login %s", user);
1.16 millert 162: if ((user = strdup(pwd->pw_name)) == NULL)
163: err(1, "can't allocate memory");
1.1 deraadt 164:
1.28 deraadt 165: #if KERBEROS
166: if (ksettkfile(user))
167: use_kerberos = 0;
168: #endif
169:
1.1 deraadt 170: if (ruid) {
171: #ifdef KERBEROS
1.21 tholo 172: if (!use_kerberos || kerberos(username, user, pwd->pw_uid))
1.1 deraadt 173: #endif
174: {
175: /* only allow those in group zero to su to root. */
1.3 deraadt 176: if (pwd->pw_uid == 0 && (gr = getgrgid((gid_t)0))
177: && gr->gr_mem && *(gr->gr_mem))
1.1 deraadt 178: for (g = gr->gr_mem;; ++g) {
1.8 millert 179: if (!*g)
180: errx(1, "you are not in the correct group to su %s.", user);
181: if (strcmp(username, *g) == 0)
1.1 deraadt 182: break;
183: }
184: /* if target requires a password, verify it */
185: if (*pwd->pw_passwd) {
186: p = getpass("Password:");
187: #ifdef SKEY
188: if (strcasecmp(p, "s/key") == 0) {
1.14 millert 189: if (skey_authenticate(user))
1.8 millert 190: goto badlogin;
1.1 deraadt 191: } else
192: #endif
193: if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) {
194: badlogin:
195: fprintf(stderr, "Sorry\n");
196: syslog(LOG_AUTH|LOG_WARNING,
197: "BAD SU %s to %s%s", username,
198: user, ontty());
199: exit(1);
200: }
201: }
202: }
1.8 millert 203: if (pwd->pw_expire && time(NULL) >= pwd->pw_expire) {
204: fprintf(stderr, "Sorry - account expired\n");
205: syslog(LOG_AUTH|LOG_WARNING, "BAD SU %s to %s%s", username,
206: user, ontty());
207: exit(1);
208: }
1.1 deraadt 209: }
210:
211: if (asme) {
212: /* if asme and non-standard target shell, must be root */
1.8 millert 213: if (!chshell(pwd->pw_shell) && ruid)
214: errx(1, "permission denied (shell).");
1.1 deraadt 215: } else if (pwd->pw_shell && *pwd->pw_shell) {
216: shell = pwd->pw_shell;
217: iscsh = UNSET;
218: } else {
219: shell = _PATH_BSHELL;
220: iscsh = NO;
221: }
222:
1.30 ! deraadt 223: if ((p = strrchr(shell, '/')))
1.1 deraadt 224: avshell = p+1;
225: else
226: avshell = shell;
227:
228: /* if we're forking a csh, we want to slightly muck the args */
229: if (iscsh == UNSET)
230: iscsh = strcmp(avshell, "csh") ? NO : YES;
231:
232: /* set permissions */
1.17 tholo 233: if (setegid(pwd->pw_gid) < 0)
234: err(1, "setegid");
1.8 millert 235: if (setgid(pwd->pw_gid) < 0)
236: err(1, "setgid");
237: if (initgroups(user, pwd->pw_gid))
238: err(1, "initgroups failed");
1.17 tholo 239: if (seteuid(pwd->pw_uid) < 0)
240: err(1, "seteuid");
1.8 millert 241: if (setuid(pwd->pw_uid) < 0)
242: err(1, "setuid");
1.1 deraadt 243:
244: if (!asme) {
245: if (asthem) {
246: p = getenv("TERM");
1.23 deraadt 247: if ((environ = calloc(1, sizeof (char *))) == NULL)
1.22 deraadt 248: errx(1, "calloc");
1.1 deraadt 249: (void)setenv("PATH", _PATH_DEFPATH, 1);
1.6 deraadt 250: if (p)
251: (void)setenv("TERM", p, 1);
1.5 deraadt 252:
253: seteuid(pwd->pw_uid);
254: setegid(pwd->pw_gid);
1.8 millert 255: if (chdir(pwd->pw_dir) < 0)
256: errx(1, "no directory");
1.5 deraadt 257: seteuid(0);
258: setegid(0); /* XXX use a saved gid instead? */
1.1 deraadt 259: }
1.15 millert 260: if (asthem || pwd->pw_uid) {
261: (void)setenv("LOGNAME", pwd->pw_name, 1);
1.1 deraadt 262: (void)setenv("USER", pwd->pw_name, 1);
1.15 millert 263: }
1.1 deraadt 264: (void)setenv("HOME", pwd->pw_dir, 1);
265: (void)setenv("SHELL", shell, 1);
266: }
267:
1.28 deraadt 268: #ifdef KERBEROS
269: if (*krbtkfile)
270: (void)setenv("KRBTKFILE", krbtkfile, 1);
271: #endif
272:
1.1 deraadt 273: if (iscsh == YES) {
274: if (fastlogin)
275: *np-- = "-f";
276: if (asme)
277: *np-- = "-m";
278: }
279:
280: if (asthem) {
281: avshellbuf[0] = '-';
1.11 millert 282: strncpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 2);
1.10 millert 283: avshellbuf[sizeof(avshellbuf) - 1] = '\0';
1.1 deraadt 284: avshell = avshellbuf;
285: } else if (iscsh == YES) {
286: /* csh strips the first character... */
287: avshellbuf[0] = '_';
1.11 millert 288: strncpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 2);
1.10 millert 289: avshellbuf[sizeof(avshellbuf) - 1] = '\0';
1.1 deraadt 290: avshell = avshellbuf;
291: }
292:
293: *np = avshell;
294:
295: if (ruid != 0)
296: syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s",
297: username, user, ontty());
298:
299: (void)setpriority(PRIO_PROCESS, 0, prio);
300:
301: execv(shell, np);
1.9 millert 302: err(1, shell);
1.1 deraadt 303: }
304:
305: int
306: chshell(sh)
307: char *sh;
308: {
309: register char *cp;
310:
311: while ((cp = getusershell()) != NULL)
1.8 millert 312: if (strcmp(cp, sh) == 0)
1.1 deraadt 313: return (1);
314: return (0);
315: }
316:
317: char *
318: ontty()
319: {
320: char *p, *ttyname();
321: static char buf[MAXPATHLEN + 4];
322:
323: buf[0] = 0;
1.30 ! deraadt 324: if ((p = ttyname(STDERR_FILENO)))
1.8 millert 325: snprintf(buf, sizeof(buf), " on %s", p);
1.1 deraadt 326: return (buf);
327: }
328:
329: #ifdef KERBEROS
1.30 ! deraadt 330: int
1.1 deraadt 331: kerberos(username, user, uid)
332: char *username, *user;
333: int uid;
334: {
335: KTEXT_ST ticket;
336: AUTH_DAT authdata;
337: struct hostent *hp;
338: int kerno;
1.27 deraadt 339: in_addr_t faddr;
1.1 deraadt 340: char hostname[MAXHOSTNAMELEN], savehost[MAXHOSTNAMELEN];
341: char *ontty(), *krb_get_phost();
342:
343: if (koktologin(username, lrealm, user) && !uid) {
344: (void)fprintf(stderr, "kerberos su: not in %s's ACL.\n", user);
345: return (1);
346: }
1.28 deraadt 347: (void)krb_set_tkt_string(krbtkfile);
1.1 deraadt 348:
349: /*
350: * Set real as well as effective ID to 0 for the moment,
351: * to make the kerberos library do the right thing.
352: */
353: if (setuid(0) < 0) {
1.8 millert 354: warn("setuid");
1.1 deraadt 355: return (1);
356: }
357:
358: /*
359: * Little trick here -- if we are su'ing to root,
360: * we need to get a ticket for "xxx.root", where xxx represents
361: * the name of the person su'ing. Otherwise (non-root case),
362: * we need to get a ticket for "yyy.", where yyy represents
363: * the name of the person being su'd to, and the instance is null
364: *
365: * We should have a way to set the ticket lifetime,
366: * with a system default for root.
367: */
368: kerno = krb_get_pw_in_tkt((uid == 0 ? username : user),
369: (uid == 0 ? "root" : ""), lrealm,
370: "krbtgt", lrealm, DEFAULT_TKT_LIFE, 0);
371:
372: if (kerno != KSUCCESS) {
373: if (kerno == KDC_PR_UNKNOWN) {
1.8 millert 374: warnx("kerberos principal unknown: %s.%s@%s",
1.1 deraadt 375: (uid == 0 ? username : user),
376: (uid == 0 ? "root" : ""), lrealm);
377: return (1);
378: }
1.8 millert 379: warnx("unable to su: %s", krb_err_txt[kerno]);
1.1 deraadt 380: syslog(LOG_NOTICE|LOG_AUTH,
381: "BAD Kerberos SU: %s to %s%s: %s",
382: username, user, ontty(), krb_err_txt[kerno]);
383: return (1);
384: }
385:
386: if (chown(krbtkfile, uid, -1) < 0) {
1.8 millert 387: warn("chown");
1.1 deraadt 388: (void)unlink(krbtkfile);
389: return (1);
390: }
391:
392: (void)setpriority(PRIO_PROCESS, 0, -2);
393:
394: if (gethostname(hostname, sizeof(hostname)) == -1) {
1.8 millert 395: warn("gethostname");
1.1 deraadt 396: dest_tkt();
397: return (1);
398: }
399:
1.11 millert 400: (void)strncpy(savehost, krb_get_phost(hostname), sizeof(savehost) - 1);
1.1 deraadt 401: savehost[sizeof(savehost) - 1] = '\0';
402:
403: kerno = krb_mk_req(&ticket, "rcmd", savehost, lrealm, 33);
404:
405: if (kerno == KDC_PR_UNKNOWN) {
1.8 millert 406: warnx("Warning: TGT not verified.");
1.1 deraadt 407: syslog(LOG_NOTICE|LOG_AUTH,
408: "%s to %s%s, TGT not verified (%s); %s.%s not registered?",
409: username, user, ontty(), krb_err_txt[kerno],
410: "rcmd", savehost);
411: } else if (kerno != KSUCCESS) {
1.8 millert 412: warnx("Unable to use TGT: %s", krb_err_txt[kerno]);
1.1 deraadt 413: syslog(LOG_NOTICE|LOG_AUTH, "failed su: %s to %s%s: %s",
414: username, user, ontty(), krb_err_txt[kerno]);
415: dest_tkt();
416: return (1);
417: } else {
418: if (!(hp = gethostbyname(hostname))) {
1.8 millert 419: warnx("can't get addr of %s", hostname);
1.1 deraadt 420: dest_tkt();
421: return (1);
422: }
1.10 millert 423: (void)memcpy((void *)&faddr, (void *)hp->h_addr, sizeof(faddr));
1.1 deraadt 424:
425: if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr,
426: &authdata, "")) != KSUCCESS) {
1.8 millert 427: warnx("unable to verify rcmd ticket: %s",
428: krb_err_txt[kerno]);
1.1 deraadt 429: syslog(LOG_NOTICE|LOG_AUTH,
430: "failed su: %s to %s%s: %s", username,
431: user, ontty(), krb_err_txt[kerno]);
432: dest_tkt();
433: return (1);
434: }
435: }
436: return (0);
437: }
438:
439: koktologin(name, realm, toname)
440: char *name, *realm, *toname;
441: {
442: register AUTH_DAT *kdata;
443: AUTH_DAT kdata_st;
444:
1.13 deraadt 445: memset((void *)&kdata_st, 0, sizeof(kdata_st));
1.1 deraadt 446: kdata = &kdata_st;
1.10 millert 447:
1.11 millert 448: (void)strncpy(kdata->pname, name, sizeof(kdata->pname) - 1);
1.10 millert 449: kdata->pname[sizeof(kdata->pname) - 1] = '\0';
450:
451: (void)strncpy(kdata->pinst,
1.11 millert 452: ((strcmp(toname, "root") == 0) ? "root" : ""), sizeof(kdata->pinst) - 1);
1.13 deraadt 453: kdata->pinst[sizeof(kdata->pinst) -1] = '\0';
1.10 millert 454:
1.11 millert 455: (void)strncpy(kdata->prealm, realm, sizeof(kdata->prealm) - 1);
1.10 millert 456: kdata->prealm[sizeof(kdata->prealm) -1] = '\0';
457:
1.1 deraadt 458: return (kuserok(kdata, toname));
1.28 deraadt 459: }
460:
461: int
462: ksettkfile(user)
463: char *user;
464: {
465: if (krb_get_lrealm(lrealm, 1) != KSUCCESS)
466: return (1);
467: (void)snprintf(krbtkfile, sizeof(krbtkfile), "%s_%s_%u", TKT_ROOT,
468: user, getuid());
469: return (0);
1.1 deraadt 470: }
471: #endif
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